Outlet valve arrangements for enhanced pump efficiency

ABSTRACT

A dispenser includes a housing, an inverted container disposed in the housing, a outlet nozzle, a pump, a first check valve, and a second check valve. The container holds a fluid. The pump is disposed between the container and the outlet nozzle. The pump includes a pump inlet in fluid communication with the container, a pump outlet in fluid communication with the outlet nozzle, and a pump chamber in fluid communication with the pump inlet and the pump outlet. The pump chamber is movable between an expanded position and a compressed position. The first check valve is disposed between the pump and the outlet nozzle, and the first check valve has a first cracking pressure. The second check valve is disposed between the first check valve and the outlet nozzle, and the second check valve has a second cracking pressure. The second cracking pressure of the second check valve is greater than the first cracking pressure of the first check valve.

RELATED APPLICATIONS

This application claims priority to and the benefits of U.S. ProvisionalPatent Application Ser. No. 62/637,487, titled Outlet Valve Arrangementfor Enhanced Pump Efficiency, which was filed on Mar. 2, 2018 and isincorporated herein by reference in its entirety.

BACKGROUND

Dispenser systems, such as soap, sanitizer, and lotion dispensers,provide a user with a selected amount of liquid upon actuation of thedispenser. Dispenser systems often use a pump to pump liquid from acontainer and into the hand of a user.

SUMMARY

An exemplary dispenser includes a housing, an inverted containerdisposed in the housing, an outlet nozzle, a pump, a first check valve,and a second check valve. The container holds a fluid. The pump isdisposed between the container and the outlet nozzle. The pump includesa pump inlet in fluid communication with the container, a pump outlet influid communication with the outlet nozzle, and a pump chamber in fluidcommunication with the pump inlet and the pump outlet. The pump chamberis movable between an expanded position and a compressed position. Thefirst check valve is disposed between the pump and the outlet nozzle,and the first check valve has a first cracking pressure. The secondcheck valve is disposed between the first check valve and the outletnozzle, and the second check valve has a second cracking pressure. Thesecond cracking pressure of the second check valve is greater than thefirst cracking pressure of the first check valve.

Another exemplary dispenser includes a housing, an inverted containerdisposed in the housing, an outlet nozzle, a pump, a first check valve,and a second check valve. The inverted container holds a liquid. Thepump is disposed between the container and the outlet nozzle. The pumpincludes a pump inlet, a pump outlet, and a pump chamber. The pump inletis in fluid communication with the container and the pump chamber, andthe pump outlet is in fluid communication with the pump chamber and theoutlet nozzle. The pump chamber is movable between an expanded positionand a compressed position. The first check valve is disposed between thepump and the outlet nozzle, and the first check valve has a crackingpressure that is less than about 0.5 psi. The second check valve isdisposed between the first check valve and the outlet nozzle, and thesecond check valve has a cracking pressure that is greater than about0.5 psi.

Another exemplary dispenser includes a housing, an actuator locatedwithin the housing, a container located within the housing, a pump, atleast one fast acting outlet valve located downstream of the pump, aslow acting outlet valve located downstream of the fast acting outletvalve, and an outlet nozzle. The container carries a fluid that includessoap, lotion, or sanitizer. The pump has an inlet, at least two pumpchambers, and an outlet. During a selected dispensing time, the fastacting outlet valve cycles open and closed at least two times for everytime the slow acting outlet valve cycles open and closed.

Another exemplary dispenser includes a housing, an actuator locatedwithin the housing, a holder for holding a container, a pump, at leasttwo outlet valves in series, and an outlet nozzle. The container holds asoap, sanitizer, or lotion. The pump has an inlet, at least one pumpchamber, and an outlet. The at least two outlet valves are locateddownstream of the pump. During a selected dispensing time, at least oneof the two outlet valves cycles open and closed at least two times forevery time a second of the two outlet valves cycles open and closed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary embodiment of adispenser having a novel outlet valve arrangement; and

FIG. 2 is a partial cross-sectional view of an exemplary embodiment of aportion of another dispenser having a novel outlet valve arrangement.

DETAILED DESCRIPTION

The Detailed Description describes exemplary embodiments of theinvention and is not intended to limit the scope of the claims in anyway. Indeed, the invention is broader than and unlimited by theexemplary embodiments, and the terms used in the claims have their fullordinary meaning. Features and components of one exemplary embodimentmay be incorporated into the other exemplary embodiments. Inventionswithin the scope of this application may include additional features, ormay have less features, than those shown in the exemplary embodiments.

FIG. 1 illustrates an exemplary dispenser 100 having a housing 102, acontainer 104 for holding a liquid, a pump 108, a first check valve 120,a second check valve 122, and a dispenser outlet 110. As shown in theillustrated embodiment, the dispenser is an inverted dispenser. The pump108 is configured to pump the liquid from the container 104 through theoutlet 110 and into the hand of a user. The liquid can be, for example,soap, a concentrated soap, a sanitizer, a lotion, a moisturizer or thelike. The pump 108 may be, for example, a displacement pump, such as,for example, a piston pump, a diaphragm pump, a rotary pump, or thelike. In certain embodiments, the pump 108 may be a sequentiallyactivated multi-diaphragm pump. Exemplary embodiments of sequentiallyactivated multi-diaphragm pumps are shown and disclosed in: U.S.Non-Provisional application Ser. No. 15/429,389 filed on Feb. 10, 2017and titled HIGH QUALITY NON-AEROSOL HAND SANITIZING FOAM; U.S.Non-Provisional application Ser. No. 15/369,007 filed on Dec. 5, 2016and titled SEQUENTIALLY ACTIVATED MULTI-DIAPHRAGM FOAM PUMPS, REFILLUNITS AND DISPENSER SYSTEMS; U.S. Non-Provisional patent applicationSer. No. 15/355,112 filed on Nov. 18, 2016 and titled SEQUENTIALLYACTIVATED MULTI-DIAPHRAGM FOAM PUMPS, REFILL UNITS AND DISPENSERSYSTEMS; U.S. Non-Provisional application Ser. No. 15/350,190 filed onNov. 14, 2016 and titled IMPROVED FOAMING CARTRIDGE; U.S.Non-Provisional application Ser. No. 15/356,795 filed on Nov. 21, 2016and titled FOAM DISPENSING SYSTEMS, PUMPS AND REFILL UNITS HAVING HIGHAIR TO LIQUID RATIOS; and U.S. Non-Provisional application Ser. No.15/480,711 filed on Apr. 6, 2017 and titled FOAM DISPENSING SYSTEMS,PUMPS AND REFILL UNITS HAVING HIGH AIR TO LIQUID RATIOS; each of whichare incorporated herein in their entirety.

In various embodiments, the dispenser 100 is a “touch free” dispenserand includes an actuator 114 that activates the pump 108 to pump liquidfrom the container 104 and out of the outlet nozzle 110 of the dispenser100. In some embodiments, the liquid is combined with air and dispensedas a foam. Exemplary touch-fee dispensers are shown and described inU.S. Pat. No. 7,837,066 titled Electronically Keyed Dispensing SystemAnd Related Methods Utilizing Near Field Response; U.S. Pat. No.9,172,266 title Power Systems For Touch Free Dispensers and Refill UnitsContaining a Power Source; U.S. Pat. No. 7,909,209 titled Apparatus forHands-Free Dispensing of a Measured Quantity of Material; U.S. Pat. No.7,611,030 titled Apparatus for Hans-Free Dispensing of a MeasuredQuantity of Material; U.S. Pat. No. 7,621,426 titled ElectronicallyKeyed Dispensing Systems and Related Methods Utilizing Near FieldResponse; and U.S. Pat. No. 8,960,498 titled Touch-Free Dispenser withSingle Cell Operation and Battery Banking; all which are incorporatedherein by reference. In embodiments that include a touch-free feature,the dispenser 100 may include a power source (not shown), a sensor (notshown) for detecting the presence of a hand, a controller (not shown),and a motor (not shown), which are all known in the art. The powersource is in electrical communication with and provides power to thesensor, controller, and motor. The power source may be an internal powersource, such as, for example, one or more batteries or an external powersource, such as, for example, solar cells, or a conventional 120 VACpower supply, or combinations thereof.

In various embodiments, the dispenser is a manual dispenser. In suchembodiments, the actuator 114 may require manual activation, such as,for example, a user engages a push bar, a user engages a foot pedal, apushbutton, or the like. In some embodiments that require manualactivation, a push bar (not shown) is mechanically coupled to the pump108 and, when a user engages the push bar, the pump causes liquid fromthe container 104 to exit the outlet nozzle 110 of the dispenser 100.

Still referring to FIG. 1, an exemplary embodiment of a pump 108includes a pump inlet 112, a pump outlet 116, and a pump chamber 118.The pump inlet 112 is in fluid communication with the container 104 suchthat the pump inlet receives liquid from the container 104. The pumpchamber 118 is in fluid communication with the pump inlet 112 such thatthe pump chamber 118 can receive liquid from the container 104 throughthe pump inlet 112. The pump outlet 116 is in fluid communication withthe pump chamber 118 and with the outlet nozzle 110 such that the pump108 can pump liquid from the pump chamber 118 through the pump outlet116 and the outlet nozzle 110. In certain embodiments, the pump 108 is apositive displacement pump such that movement of the pump chamber 118between an expanded position and a compressed position causes the pump108 to pump liquid through the outlet nozzle 110 of the dispenser 100and to move liquid from the container 104 and into the pump chamber 118.In certain embodiments, the pump chamber 118 has a small volume. Incertain embodiments, the volume of pump chamber 118 is between about 0.2cc and about 0.5 cc when the pump chamber 118 is in the expandedposition.

The dispenser 100 includes a first check valve 120 and a second checkvalve 122. Both the first check valve 120 and the second check valve 122are disposed between the pump 108 and the outlet nozzle 110. The firstcheck valve 120 may be a normally closed valve disposed adjacent to theoutlet 116 of the pump 108. In some embodiments, first check valve 120may be normally open or have minimal to no cracking pressure. Firstcheck valve 120 is a fast acting valve.

Movement of the first check valve 120 from the closed position to anopen position allows liquid in the pump chamber 118 to move past thefirst check valve 120 and into the area 121 between the first checkvalve 120 and the second check valve 122. Movement of the first checkvalve 120 from the open position back to the closed position preventsfluid, i.e. air or liquid, from flowing into the pump chamber 118 fromthe area 121 between the first check valve 120 and the second checkvalve 122.

It is advantageous to prevent air from entering the pump chamber 118(during, for example, priming and use of the dispenser 100) from thearea between first check valve 120 and second check valve 122, becauseair being compressed in the pump chamber 118 (and/or air in the pumpchamber and the air between first check valve 120 and second check valve122) affects the efficiency of the pump 108 and/or may prevent the pump108 from priming. That is, if air enters the pump chamber 118 from area121, during priming of the pump 108, the air will occupy a portion ofthe volume of the pump chamber 118, which will lead to less liquid, orno liquid at all, being pulled into the pump chamber 118. In addition,because air is more compressible than liquid, air in the pump chamber118 may readily compress and expand with expansion and compression ofthe pump chamber 118 and not pump any liquid, or pump smaller doses ofliquid than desired. In some embodiments, it is preferred that the fistcheck valve 120 is located as close as possible to the downstream end ofthe pump chamber 118. The term pump outlet is used broadly herein andthe first check valve 120 may be located in or at the opening of thepump outlet 116 from the pump chamber 118.

In certain embodiments, the first check valve 120 is a high flow, fastacting valve. For example, in some embodiments, the first check valvecloses in less than about 0.1 seconds. In some embodiments, uponactivation of the pump 108 (for example, using a sequentially activateddiaphragm pump), the first check valve 120 will move from the closedposition to the open position between about 5 times and about 20 timesin about 0.5 seconds, such as, for example, about 10 times in 0.5seconds. In certain embodiments, first check valve 120 has minimalcracking pressure. For example, in some embodiments, the crackingpressure of the first check valve 120 is between about 0 psi and about 2psi. The first check valve 120 can be, for example, an umbrella valve, aduckbill valve, a flapper valve, or the like.

The second check valve 122 is disposed between the first check valve 120and the outlet nozzle 110. The second check valve 122 is a normallyclosed valve. The second check valve 122 is configured to prevent liquidfrom flowing out of the outlet nozzle 110 of the dispenser 100 when thepump 108 is not in operation. Movement of the second check valve 122from the closed position to an open position allows fluid in area 121 toexit the outlet nozzle 110 of the dispenser 100 and be dispensed intothe hand of a user. After the fluid stops moving past the second checkvalve 122 and through the outlet nozzle 110, the second check valve 122returns to the closed position, which prevents residual fluid in area121 from flowing out of the dispenser 100 through outlet nozzle 110.Accordingly, the second check valve 122 acts as an anti-drip mechanism.In some embodiments, the second check valve 122 is a slow reacting highflow check valve. For example, in some embodiments, upon activation ofthe pump 108, the second check valve 122 remains in the open positionfor between about 0.25 seconds and about 0.75 seconds, such as about 0.5seconds even though the first check valve 120 is opening and closingmultiple times during the same time period. In certain embodiments, thesecond check valve 122 has a cracking pressure of 0.5 psi or greater,such as 0.75 psi or greater, such as 1 psi or greater, such as 1.25 psior greater. The second check valve 122 can be, for example, a ball andspring valve, a mushroom valve, a flapper valve, or the like.

In certain embodiments, the second check valve 122 has a greatercracking pressure than the first check valve 120. In variousembodiments, the second check valve 122 can have a cracking pressurebetween about 0.5 psi and about 3 psi, and the first check valve 120 canhave a cracking pressure between about 0 psi and about 2 psi. In certainembodiments, the ratio of cracking pressure for the second check valve122 to the cracking pressure for the first check valve 120 can bebetween about 2 to 1 and about 4 to 1. In alternative embodiments, theratio of cracking pressure for the second check valve 122 to thecracking pressure of the first check valve 120 can be greater than 4 to1, such as for example, 5 to 1, 6 to 1, 7 to 1, 8 to 1, 9 to 1, 10 to 1,11 to 1 and 12 to 1.

To operate the dispenser 100, a user activates the pump 108 using theactuator 114, which causes fluid to flow from the pump chamber 118,through the outlet nozzle 110, and into a hand of the user. Activationof the pump 108 causes the pump chamber 118 to move from an expandedposition to a compressed position, which causes the fluid in the pumpchamber 118 to travel through the pump outlet 116 and engage the firstcheck valve 120 such that a force is applied to the first check valvethat causes the first check valve 120 to move to an open position. Thatis, the force applied by the fluid creates a pressure on the first checkvalve 120 that exceeds the cracking pressure of the first check valve,which causes the first check valve 120 to move to the open position.Movement of the first check valve 120 to the open position allows thefluid to move past the first check valve 120 and into the area 121between the first check valve 120 and the second check valve 122. Asfluid moves into the area 121, the fluid engages the second check valve122 and applies a force to the second check valve 122 that causes thesecond check valve 122 to move to an open position. That is, the forceapplied by the fluid (from activation of the pump 108) creates apressure on the second check valve 122 that exceeds the crackingpressure of the second check valve 122, which causes the second checkvalve 122 to move to the open position. Movement of the second checkvalve 122 to the open position allows the fluid to move past the secondcheck valve 122, through the outlet nozzle 110 of the dispenser 100, andinto the hand of a user. The contraction of pump chamber 118 also causesfirst check valve 120 to rapidly close in order to prevent fluid frombeing drawn in from area 121 and forcing fluid to be drawn in fromcontainer 104.

After any air from upstream of the pump chamber 118 exits the pumpchamber 118, the pump 108 is primed (i.e., fluid is moved from thecontainer 104 and into the pump chamber 118) such that anotheractivation of the pump 108 causes fluid to be pumped toward the outletnozzle 110 of the dispenser 100. When the pump chamber 118 fullycompresses, fluid flow stops and the force applied by the fluid on thefirst check valve 120 decreases until the pressure applied on the firstcheck valve 120 is less than the cracking pressure of the first checkvalve, which may cause the first check valve 120 to return to the closedposition. In some embodiments, first check valve 120 does not return toa closed position until a negative pressure develops in pump chamber 118(i.e. the pump chamber 118 begins to expand). As the fluid flow stops,the force applied by the liquid on the second check valve 122 willdecrease until the pressure applied on the second check valve 122 isless than the cracking pressure of the second check valve, which willcause the second check valve to return to the closed position. Expansionand contraction of the pump chamber 118 cause the first check valve 120to close and open respectively. In some embodiments, the opening andclosing of first check valve 120, and hence the expansion andcontraction of the pump chamber 118 happens fast enough that sufficientfluid flow continues through area 121 to keep second check valve 122open. In many embodiments, there are more than one pump chambers 118feeding area 121. In some embodiments multiple pump chambers 118 aresequenced so that one pump chamber 118 is expanding while another pumpchamber is compressing, thus helping maintain a constant flow of fluidthrough area 121 and past second check valve 122.

In some embodiments, the volume of area 121 is greater than the volumeof pump chamber 118. In some embodiments, the volume of area 121 is twoore more times the volume of pump chamber 118. In some embodiments, thevolume of area 121 is three or more times the volume of pump chamber118. In some embodiments, the volume of area 121 is four or more timesthe volume of pump chamber 118. In some embodiments, the volume of area121 is five or more times the volume of pump chamber 118.

As the pump chamber 118 moves from the compressed position to theexpanded position, a negative pressure is created in the pump chamber118. The negative pressure in the pump chamber 118 causes liquid fromthe container 104 to enter the pump chamber through the pump inlet 112.In some embodiments, the first check valve 120 is advantageous becauseit prevents air and/or liquid in the area 121 from entering the pumpchamber 118 through the pump outlet 116. If air and/or residual liquidenter the pump chamber 118 through the pump outlet 116 during operationof the pump 108, and, in particular, during priming of the pump, thepump 108 may be less efficient and possibly not prime. In someembodiments, the second check valve 122 is advantageous because itprevents residual fluid in the area 121 from dripping through the outletnozzle 110 between activations of the pump 108.

FIG. 2 illustrates a cross sectional view of a portion of an exemplarydispenser 200 having a novel outlet valve arraignment. Dispenser 200includes a pump 208, a first check valve 220, a second check valve 222,and an outlet nozzle 210. The pump includes a pump inlet (not shown)that is in fluid communication with a container (not shown) of thedispenser 200, a pump chamber 218, and a pump outlet 216. The pump 208is an inverted setup, i.e. a container (not shown) full of fluid is influid communication with the pump chamber 218 and is positioned so thatat least a portion of the fluid in the container is located above thepump chamber 218. The pump chamber 218 is movable between an expandedposition and a compressed position.

In certain embodiments, the pump chamber 218 includes a compressibleportion 217 and a non-compressible portion 219. The volume of thecompressible portion 217 of the pump chamber 218 moves between anexpanded volume (i.e., the volume of the pump in the expanded state) anda compressed volume when the pump chamber is in the compressed state.The volume of the non-compressible portion 219 of the pump chamber 218remains constant. In certain embodiments, the volume of the compressibleportion 217 is between about 80% and about 100% of the volume of theentire pump chamber (i.e., the volume of both the compressible portion217 and the non-compressible portion 219). In some embodiments, it isadvantageous to have a pump chamber 218 that includes a compressibleportion 217 that has a volume between 80% and 100% of the volume for theentire pump chamber because a positive displacement pump is moreefficient if a larger portion of the volume for the pump chamber iscompressible. In certain embodiments, the pump chamber 218 is a smallpump chamber. For example, the pump chamber 218 can have a volumebetween about 0.2 cc and about 0.5 cc when the pump chamber is in theexpanded position.

The first check valve 220 and the second check valve 222 are disposedbetween the pump 208 and the outlet nozzle 210. The first check valve220 is disposed between the pump 208 and the second check valve 222. Incertain embodiments, the first check valve 220 is disposed adjacent tothe pump chamber 218 of the pump 208. In some embodiments, the firstcheck valve 220 is disposed a distance X away from the compressibleportion 217 of the pump chamber 218. The distance X can be, for example,between about 0 inches and about 0.375 inches, such as between about0.125 inches and about 0.25 inches. In certain embodiments, the distanceX can be 0.5 inches or less, such as about 0.375 inches or less, such asabout 0.25 inches or less, such as about 0.125 inches or less.

In some embodiments, the first check valve 220 is a normally closedvalve that prevents liquid from exiting the pump chamber 218 through thepump outlet 216 when the first check valve 220 is in a closed position.In some embodiments, first check valve 220 has a neutral state or has avery slight cracking pressure to open, provided that first check valve220 quickly closes upon minimal vacuum pressure in pump chamber 218.Movement of the first check valve 220 from the closed position to anopen position allows liquid in the pump chamber 218 to move past thefirst check valve 220 and into the area 221 between the first checkvalve and the second check valve 222. Movement of the first check valve220 from the open position back to the closed position prevents liquidand/or air from entering the pump chamber 218 from area 221 of the pump208. It is advantageous to prevent air from entering the pump chamber218 (during, for example, priming and use of the dispenser 200) becauseair being compressed in the pump chamber 218 affects the efficiency ofthe pump 208. That is, if air enters the pump chamber 218 during primingof the pump, the air will occupy a portion of the volume of the pumpchamber, which may lead to less fluid being drawn in the pump chamber218, or simply compressing and decompressing the air in the pump chamber218 resulting in the pump 208 not priming or taking a long period oftime to prime.

In some embodiments, upon activation of the pump 208, the first checkvalve 220 will rapidly move between the closed position and the openposition between about 5 times and about 20 times in about 0.5 seconds,such as about 10 times in about 0.5 seconds. In certain embodiments, thefirst check valve 120 is a high flow, fast acting valve. For example, insome embodiments, the first check valve 220 closes in less than about0.1 seconds. In certain embodiments, first check valve 120 has minimalcracking pressure. For example, the cracking pressure of the first checkvalve 120 is between about 0 psi and about 2 psi. In the illustratedembodiment, the first check valve 220 is an umbrella valve. Inalternative embodiments, the first check valve can be a duckbill valve,a flapper valve, or the like.

In certain embodiments, the pump 208 is a sequentially-activatedmulti-diaphragm pump that has a plurality of pump chambers (e.g., thepump chamber 218 described above). In some of these embodiments, a checkvalve (e.g., the first check valve 220 described above) may be disposedadjacent to each of the pump chambers such that each of the check valvesis disposed between the corresponding pump chamber and the second checkvalve 222. In other embodiments, a single check valve (e.g., the firstcheck valve 218 described above) may be disposed adjacent to all of thepump chambers such that the single check valve is disposed between eachof the pump chambers and the second check valve 222. In theabove-mentioned embodiments, the check valve(s) between the pumpchambers and the second check valve 222 may take any form and act in anymanner described herein with regard to the first check valve 220. In theabove-mentioned embodiments, the check valve(s) 220 between the pumpchambers and the second check valve 222 may rapidly move between theclosed position and the open position upon activation of the pump. Forexample, the check valve(s) 220 may move between closed position and theopen position between about 5 times and about 20 times in about 0.5seconds, such as about 10 times in about 0.5 seconds. In addition, inthe above-mentioned embodiments, the check valve(s) may be high flow,fast acting valves that close in less than about 0.1 seconds. The checkvalve(s) may also have a minimal cracking pressure, such as, forexample, between about 0 psi and about 2 psi. The check valve(s) may bean umbrella valve, a duckbill valve, a flapper valve, or the like.

In this exemplary embodiment, the second check valve 222 includes amushroom member 226 and a biasing member 228 (e.g., a spring). Othercheck valves with similar properties may be used, such as, for example,a spring and ball valve. The second check valve 222 is movable betweenan open position and a closed position. The second check 222 valve is inthe closed position when the mushroom member 226 engages an sealingsurface 231 of the area 221, and the second check valve 222 is in theopen position when the mushroom member 226 is moved away from thesealing surface 231 in the direction D. In certain embodiments, thesecond check valve 222 is a normally closed valve, in which the biasingmember 228 exerts a force on the mushroom member 226 in the direction Zthat causes the second check valve to maintain the closed position. Whenthe second check valve 220 is in the closed position, fluid in the area221 is prevented from moving past second check valve 220 and outletnozzle 210. Movement of the mushroom member 226 in the direction D movesthe second check valve 222 to the open position and allows fluid fromthe area 221 to move past second check valve 222 and through the outletnozzle 210. In certain embodiments, the second check valve 222 is a highflow valve that is configured to prevent static drip of fluid from theoutlet nozzle 210 when the second check valve 222 is in the closedposition. In some embodiments, the second check valve 222 is a slowacting check valve that, for example, has a cracking pressure of 0.5 psior greater, such as 0.75 psi or greater, such as 1 psi or greater, suchas 1.25 psi or greater. In some embodiments, upon activation of the pump208, the second check valve 222 will remain in the open position forbetween about 0.25 seconds and about 0.75 seconds (the operating time todispense a selected dose of fluid), such as about 0.5 seconds eventhough first check valve 220 opens and closes multiple times in thatsame time period. In the illustrated embodiment, the second check valve222 is a mushroom valve. In alternative embodiments, the second checkvalve 222 can be, for example, a ball and spring valve, a flapper valve,or the like.

In certain embodiments, the second check valve 222 has a greatercracking pressure than the first check valve 220. In variousembodiments, the second check valve 222 has a cracking pressure betweenabout 0.5 psi and about 3 psi, and the first check valve 220 has acracking pressure between about 0 psi and about 2 psi. In certainembodiments, the ratio of cracking pressure for the second check valve222 to the cracking pressure for the first check valve 220 is betweenabout 2 to 1 and about 4 to 1. In alternative embodiments, the ratio ofcracking pressure for the second check valve 222 to the crackingpressure of the first check valve 220 can be greater than 4 to 1.

To operate the dispenser 200, a user activates the pump 208 using theactuator (not shown), which causes fluid to flow from the pump chamber218, through the outlet nozzle 210, and into a hand of the user.Activation of the pump 208 causes the pump chamber 218 to move from anexpanded position to a compressed position, which causes the fluid inthe pump chamber 218 to travel through the pump outlet 216 past thefirst check valve 220 with a force sufficient to cause the first checkvalve 220 to move to an open position. That is, the force applied by thefluid creates a pressure on the first check valve 220 that exceeds thecracking pressure of the first check valve 220 which causes the firstcheck valve 220 to move to the open position. Movement of the firstcheck valve 220 to the open position allows the fluid to move past thefirst check valve 220 and into the area 221 between the first checkvalve 220 and the second check valve 222. As fluid moves through thearea 221, the fluid engages the second check valve 222 with a force isapplied to the mushroom member 226 of the second check valve 222sufficient to cause the mushroom member 226 to move to an open positionin the direction D. That is, the force applied by the fluid (fromactivation of the pump) also creates a pressure on the second checkvalve 222 that exceeds the cracking pressure of the second check valve,which causes the second check valve to move to the open position.Movement of the second check valve 222 to the open position allows thefluid to flow past the second check valve 222, through the outlet nozzle210 of the dispenser 200, and into the hand of a user. The contractionof pump chamber 218 also causes first check valve 120 to rapidly closein order to prevent fluid from being drawn in from area 221 and forcingfluid to be drawn in from container.

After air from upstream of the pump chamber 218 exits the pump chamber218, the pump 208 is primed (i.e., fluid is moved from the container andinto the pump chamber 218) such that another activation of the pumpcauses fluid to be pumped toward the outlet nozzle 210 of the dispenser200. In some embodiments, multiple pump chambers 218 are used. In someembodiments, one or more of the multiple pump chambers 218 pump air, andthus do not need to prime and the remaining pump chambers 218 pumpliquid. In some embodiments, the one or more pump chambers 218 pump amixture of liquid and air, and thus are primed when a selectedpercentage of the volume comprises liquid. As the pump chamber 218 isfully compressed, the force applied by the liquid on the first checkvalve 220 will decrease until the pressure applied on the first checkvalve is less than the cracking pressure of the first check valve, whichmay cause the first check valve 220 to return to the closed position. Insome embodiments, first check valve 220 does not return to a closedposition until a negative pressure develops in pump chamber 218. As thefluid stops flowing out of the outlet nozzle 210, the force applied bythe liquid on the second check valve 222 will decrease until thepressure applied on the second check valve 222 is less than the crackingpressure of the second check valve, which will cause the second checkvalve 222 to return to the closed position.

As the pump chamber 218 moves from the compressed position to theexpanded position, a negative pressure is created in the pump chamber218. The negative pressure in the pump chamber 218 causes liquid fromthe container to enter the pump chamber through the pump inlet 212 andcauses the first check valve 220 to close. In some embodiments, thefirst check valve 220 is advantageous because it prevents air and/orliquid in the area 221 from entering the pump chamber 218 through thepump outlet 216. If air and/or residual liquid enter the pump chamber218 through the pump outlet 116 during operation of the pump 208, and,in particular, during priming of the pump, the pump 208 may be lessefficient and possibly not prime. In some embodiments, the second checkvalve 222 is advantageous because it prevents residual fluid in the area221 from dripping through the outlet nozzle 210 between activations ofthe pump 208.

The exemplary embodiments of the pumps, first check valves, and secondcheck valves described herein can be part of a replaceable refill unitfor a dispenser, or can be fixed to the housing of a dispenser. Inaddition, the exemplary first and second check valves described hereincan be disposed within the housing of the pump, or can be separate fromthe pump.

While various inventive aspects, concepts and features of the inventionsmay be described and illustrated herein as embodied in combination withexemplary embodiments, these various aspects, concepts and features maybe used in many alternative embodiments, either individually or invarious combinations and sub-combinations thereof. Unless expresslyexcluded herein, all such combinations and sub-combinations are intendedto be within the scope of the present inventions. Still further, whilevarious alternative embodiments as to the various aspects, concepts andfeatures of the inventions—such as alternative materials, structures,configurations, methods, circuits, devices and components, software,hardware, control logic, alternatives as to form, fit and function, andso on—may be described herein, such descriptions are not intended to bea complete or exhaustive list of available alternative embodiments,whether presently known or later developed. Those skilled in the art mayreadily adopt one or more of the inventive aspects, concepts or featuresinto additional embodiments and uses within the scope of the presentinventions even if such embodiments are not expressly disclosed herein.Additionally, even though some features, concepts or aspects of theinventions may be described herein as being a preferred arrangement ormethod, such description is not intended to suggest that such feature isrequired or necessary unless expressly so stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure; however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Moreover, whilevarious aspects, features and concepts may be expressly identifiedherein as being inventive or forming part of an invention, suchidentification is not intended to be exclusive, but rather there may beinventive aspects, concepts and features that are fully described hereinwithout being expressly identified as such or as part of a specificinvention. Descriptions of exemplary methods or processes are notlimited to inclusion of all steps as being required in all cases, nor isthe order that the steps are presented to be construed as required ornecessary unless expressly so stated.

I/We claim:
 1. A dispenser comprising: a housing; an container disposedin the housing for holding a liquid; the container having a liquidoutlet located proximate the bottom of the container; an outlet nozzle;and a pump disposed between the container and the outlet nozzle, thepump having: a pump inlet in fluid communication with the liquid outletof the container; a pump outlet in fluid communication with the outletnozzle; a pump chamber in fluid communication with the pump inlet andthe pump outlet, wherein the pump chamber is movable between an expandedposition and a compressed position; a first check valve disposed betweenthe pump and the outlet nozzle, wherein the first check valve has afirst cracking pressure; and a second check valve disposed between thefirst check valve and the outlet nozzle, wherein the second check valvehas a second cracking pressure; wherein the second cracking pressure ofthe second check valve is greater than the first cracking pressure ofthe first check valve.
 2. The dispenser of claim 1, wherein movement ofthe pump chamber from the expanded position to the compressed positioncauses the first check valve to move to an open position such that afluid flows from the pump chamber, past the first check valve, past thesecond check valve, and out of the outlet nozzle.
 3. The dispenser ofclaim 1, wherein the first check valve is a normally-closed valve. 4.(canceled)
 5. (canceled)
 6. (canceled)
 7. The dispenser of claim 1,wherein the second check valve is a normally-closed valve.
 8. Thedispenser of claim 1, wherein the second check valve comprises a biasingmember to urge a valve member against a valve seat.
 9. (canceled) 10.(canceled)
 11. (canceled)
 12. The dispenser of claim 1, wherein the pumpis a sequentially activated multi-diaphragm pump having a plurality ofpump chambers.
 13. The dispenser of claim 12, further comprising a thirdcheck valve disposed between the pump and the second check valve;wherein movement of a first pump chamber causes the first check valve tomove to an open position such that fluid flows from the first pumpchamber, past the first check valve, past the second check valve, andout of the outlet nozzle; and wherein movement of a second pump chambercauses the third check valve to move to an open position such that fluidflows from the second pump chamber, past the third check valve, past thesecond check valve, and out of the outlet nozzle.
 14. (canceled)
 15. Thedispenser of claim 1, wherein the first cracking pressure of the firstcheck valve is between about 0 psi and about 2 psi.
 16. The dispenser ofclaim 1, wherein the second cracking pressure of the second check valveis between about 0.5 psi and about 3 psi.
 17. The dispenser of claim 1,wherein a ratio of the second cracking pressure to the first crackingpressure is between about 2 to 1 and about 4 to
 1. 18. A dispenser fordispensing soap, sanitizer or lotion comprising: a housing; an containerhaving a liquid outlet located proximate the bottom of the containerdisposed in the housing holding a soap, a sanitizer or a lotion; anoutlet nozzle; and an pump disposed between the container and the outletnozzle, the pump having: a pump inlet in fluid communication with thecontainer; a pump outlet in fluid communication with the outlet nozzle;a pump chamber in fluid communication with the pump inlet and the pumpoutlet, wherein the pump chamber is movable between an expanded positionand a compressed position; a first check valve disposed between the pumpoutlet and the outlet nozzle. the first check valve having a crackingpressure that is less than about 0.5 psi; a second check valve disposedbetween the first check valve and the outlet nozzle, the second checkvalve having a cracking pressure that is greater than about 0.5 psi. 19.The dispenser of claim 18, wherein the first check valve is anormally-closed valve.
 20. (canceled)
 21. (canceled)
 22. (canceled) 23.(canceled)
 24. The dispenser of claim 18, wherein the second check valvecomprises a sealing member and a biasing member.
 25. (canceled) 26.(canceled)
 27. The dispenser of claim 18, wherein the pump is adiaphragm pump.
 28. The dispenser of claim 18, wherein the pump is asequentially activated multi-diaphragm pump having a plurality of pumpchambers.
 29. The dispenser of claim 28, further comprising a thirdcheck valve disposed between the pump and the second check valve;wherein movement of a first pump chamber causes the first check valve toopen and close; and wherein movement of a second pump chamber causes thethird check valve to open and close; and wherein fluid that flows pastthe first check valve and the third check valve, causes the second checkvalve to open to allow the fluid to flow past.
 30. The dispenser ofclaim 29, wherein each pump chamber has a volume of between about 0.2 ccand about 0.5 cc when the pump chamber is in the expanded position. 31.The dispenser of claim 18, wherein the pump chamber has a volume ofbetween about 0.2 cc and about 0.5 cc when the pump chamber is in theexpanded position.
 32. The dispenser of claim 18, wherein a ratio of thesecond cracking pressure to the first cracking pressure is between about2 to 1 and about 4 to
 1. 33. A dispenser comprising: a housing; anactuator located within the housing; a container located within thehousing; the container carrying a fluid that includes a soap, a lotion,or a sanitizer; a pump; the pump having an inlet; at least two pumpchambers; and an outlet; at least one fast acting outlet valve locateddownstream of the pump outlet; a slow acting outlet valve locateddownstream of the at least one fast acting outlet valve; and an outletnozzle; wherein, during a selected dispensing time, the fast actingoutlet valve cycles open and closed at least two times for every timethe slow acting outlet valve cycles open and closed.
 34. (canceled) 35.(canceled)
 36. (canceled)